Using Carbon Dioxide Concentration to Assess Indoor Air Quality in Offices

Abstract

Carbon dioxide (CO 2 ) concentration is commonly used as a surrogate indicator for assessing indoor air quality (IAQ) and ventilation efficiency. The measurement and analysis of average indoor CO 2 concentration is useful to understand the performance of a ventilation system. However, uncertainties due to the ventilation rate effectiveness as well as the initial state, build-up, fluctuation, and decay of indoor CO 2 concentration from occupant load variation have not been addressed in many measurements; considerable measurement efforts are obligatory. This study, taking the long-term CO 2 measurement and occupant profile of a typical open-plan office building as reference, has developed a database to examine the probable errors of an alternative sampling scheme for assessing indoor CO 2 level in which the average pollutant concentration is obtained from two short sampling periods in two sampling sessions when the building is occupied. The results show that the assessed CO 2 level deviates from the long-term average and the probable errors correlate with the required measurement time and occupant load profile. At certain confidence levels, the potential reductions in measurement time of the alternative scheme, as compared with an 8-h continuous one, will be up to 30%, some 20% less than the reduction of measurement time for assessing indoor radon level.

A Method of Multi-Attribute Assessment Using Ideal Alternative: Choosing an Apartment With Optimal Indoor Environment

“…However, first of all it is necessary to choose attributes of the assessment. Hui et al (2007Hui et al ( , 2008 analyse indoor air quality and ventilation efficiency according to carbon dioxide (co 2 ). However, other indicators are not taken into account.…”

The effect of vent inlet aspect ratio and its location on ventilation efficiency

“…CO 2 emitted by residents is the main indoor pollutant, and indoor CO 2 concentration is a good indicator to evaluate IAQ, especially in high-density buildings. [34][35][36] In this study, the average CO 2 volume concentration in the breathing zone was used to evaluate the IAQ. Two methods, experiment and simulation, were used to carry out this study.…”

Ventilation inlets design based on ventilation performance assessment using a dimensionless time scale

“…particles) to minimize exposure risks to occupants. 6–9 Indoor CO 2 can be considered as a good indicator of IAQ, 10–12 especially in the high-density buildings, 13–18 where the CO 2 emitted by occupants can be seen as the main indoor pollutant. For instance, IAQ is considered acceptable by maintaining a steady-state CO 2 concentration no greater than 700 ppm above outdoor air level in a living space, based on the ASHRAE 62–2013 Ventilation Standard.…”